DAFX: Digital Audio Effects, Second Edition

9.1 Introduction

The idea of controlling a sound transformation according to the musical scene it is displayed in may be as old as the idea of composition. The particular case of adaptive DAFX is when the sound to be transformed is also used as the source of the modification control parameter(s): some information about the sound is then collected and used to modify the sound with a coherent evolution. With such a perspective, adaptive DAFX can be considered as an extension of, or inspired by, composition processes similar to counterpoint. This process can also be compared to what happens in natural physical phenomena, such as the harmonic enrichment happening in brass instruments when the sound level increases. This chapter presents and formalizes the use of adaptive control in order to build new digital audio effects. It presents a general framework that encompasses existing DAFX and opens doors to the development of new and refined DAFX. It is aimed at presenting the adaptive control of effects, describing the steps to build an adaptive effect and explaining the necessary modifications of signal-processing techniques.

Adaptive DAFX can be developed and used with various goals in mind: to provide a high-level control for usual DAFX, to propose new production and/or creative tools by offering new DAFX, or to strengthen the relationship between Fx, control and perception. The control and mapping aspects of adaptive DAFX are important matters. In any DAFX, the control is sometimes ...